The global positioning system (GPS) is the primary means of obtaining position, navigation, and timing (PNT) information, yet GPS receivers are vulnerable to jamming and interference due to their low expected signal strength and corresponding sensitivity. Because of these issues, a robust navigation alternative is desired for some sensitive applications, such as military and defense applications.
Terrestrial-based very low frequency (VLF; e.g., 3-30 kHz) and low frequency (LF; e.g., 30-300 kHz) beacons offer a compelling solution to this problem due to their ability to transmit PNT information over long distances using the Earth's ionosphere waveguide. Such beacons may also be of particular use in GPS-denied applications and underwater communication. However, the use of large and heavy coil inductors (which may be several m3 in volume, with weights of about 450 kg) for impedance matching typically leads to these systems having massive antennas (e.g., >300 m in height and 2.5 km2 in area), which significantly limit their deployment.
What is desired is a means for enabling new compact VLF/LF beacons, transmitters, and/or receivers with the ability to enable long range transmission of information (e.g., PNT information) from widely deployable and more easily relocatable stations.
The above information disclosed in this Background section is only for enhancement of understanding of the invention, and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art.